There are many instances where it is desirable to evenly divide flow from a single fluid line to and between a plurality of fluid lines, which will be referred to as distribution lines. Where the fluid is relatively clean and one not significantly viscous, one can employ flow impedance in each of the distribution lines. However, where the fluid is significantly viscous or contains a large proportion of particles, more or less in suspension, as with certain fertilizers, clogging will most certainly occur. Of the systems known to the applicant, the most pertinent will be described here.
Perhaps the earliest system is illustrated in U.S. Pat. No. 791,425 wherein inlet flow enters the center of a tubular distributor and is directed onto a centrally positioned cone and then into compartments positioned circumferentially around the cone. Each compartment contains an outlet to a distribution line. The problem with this arrangement is that variations in the constituency of the fluid often produce unevennesses in distribution, and the tolerances required to evenly divide a stream of, say, 1/4" in diameter, are difficult to maintain. Also, the effect of wear on the cone and orifice shortens the life of the system.
A second and somewhat related system substitutes in place of a conical receiver a nozzle which forms a conical shape flow. A basic problem with this is that nozzles do not have a uniform pattern at all pressures, and second, operation is restricted to employment with a rather limited range of inlet fluid pressures, for example, from about 20 to 40 PSI to obtain even a reasonable pattern. The significance of this limitation is that the volume of fluid distributed is a direct function of the square root of pressure. Since often, particularly in the case of fertilizer, the necessary or desired rates of application may vary beyond such a range, this limitation creates quite a problem. Additionally, the effect of wear on the nozzle is quite pronounced and flow patterns change rapidly.
In a third system, a pressurized fluid is directly distributed between a plurality of output lines, and in each line there is a flow regulator or impedance as referred to above. In this case, the flow impedance is distributed in each line, being in the form of a number of serially arranged orifices. Theoretically, if each of these orifices is alike, there will be an even flow out of each. Unfortunately, to obtain practical ranges of flow with "dirty" materials, the diameter of the orifices must be so small that clogging occurs. It is not practical to strain out these particles since they contain plant nutrients.
A fourth and somewhat related system employs one or two serially arranged orifices as impedances in output lines, and in recognition of a critical pressure situation with this system, a sight glass indicator of pressure is employed. This sight glass is several feet height, and typically there are several distributors and an operator must watch several of these sight glasses in order to properly maintain operation. This is frequently quite difficult, particularly since the operator is often engaged in driving a tractor at the same time. A further difficulty with this system is, as in the case of the third system, that it involves orifice restrictions to develop uniform impedance and plugging or partial plugging of orifices often interferes with uniformity.
It is the purpose of the applicant's invention to overcome the aforesaid and other difficulties and to provide an improved fluid distributor which will work well with either clear fluids or fluids containing suspended matter, one that does not require close operator supervision, and one that does not involve small restrictive nozzles. Further, and quite significant, the applicant's system is capable of operating over a wide pressure range, enabling a much greater range of flow rates.